Organic contaminants in wastewaters are often treated by digesting the organic materials using activated sludges composed of a biomass of microorganisms such as bacteria. Typically the activated sludge is mechanically aerated to provide a highly aerobic environment in which the microorganisms may consume the organic contaminants via aerobic digestion. While effective, aerated sludges require a significant energy input to keep the sludge throughly mixed and aerated.
Anaerobic digestion of organic wastes is also known. However, anaerobic digestion has generally been found to be significantly slower than aerobic digestion and thus requires significantly larger digestion tanks than aerobic digestion processes.
What is needed therefore, is a process for the digestion of organic wastes using activated sludge which has a reduced energy input requirement but which also allows for the rapid digestion of the wastes by the sludge microorganisms.